Which of these amps would be a good 1st amp?

Discussion in 'Amateur Radio Amplifiers' started by KF5PAL, Feb 21, 2013.

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  1. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I'd hope it's a very powerful inverter that doesn't mind large and fast load changes. The AL-811 can draw 10A or so peak (at 120Vrms), and only about 1A in standby, and in operation that transition occurs rapidly and often. With an 80% efficient inverter, this translates to currents changing from 15A (standby) to 125A (peak) at 12 Vdc.
  2. K6LZX

    K6LZX Ham Member QRZ Page

    I'd probably size a dedicated inverter to power the amp at nominal 2 or 3kw, ie plenty of power - but I am interested in the effect(s) on the amp and the output signal that might accrue due to the inverter output waveform, eg "modified squarewave" v sinewave. Keeping the dedicated battery in float or very close to float is cheap and easy using discarded (unregulated) transformer type "power converters" salvaged from old RV sources. (I'm looking at a pair of 50 amp 12 volt supplies on the bench right now.) Modern inverters are usually microprocessor controlled, better than 90 to 95% efficient, but the idea that inverter load response might have excessive latency had not occurred to me. Thanks! I'll check into that question.

    The main power shack (MPS) here provides 220 volt xtal controlled 60 cycle from a pair of 180 degree out of phase Xantrex 1224 inverters, nominal 2400 watts each and each a solid 118 volt, which seem to respond to house load changes nicely - but whether or not an Nth inverter would also do so is an unknown. The total power available via the solar array is about 1.5 kw - and that was one consideration in examining the AL811H - total required power input. Of course the main battery is 12000 + kwh - but the equilibrium load available to the station without starting a DC generator is about 1.5 kw, minus a couple of hundred watts for house load. My line voltage variations are mostly due to a longish 8 AWG wire run of 225 (one-way) feet between the power shack and the hamshack - when a reefer kicks in the lights dim for a moment. The buffer battery for the FT897 is, by the way, not the same buffer battery that I contemplate using to supply the inverter that would presumably supply the amplifier.

    (If the situation seems a bit mickey-mouse - it is. It is also, so far, very reliable, with zero unintended power outages in 8 years and zero money going out to enrich the coffers of the power company...no power bills last 10 years - and zero power-line noise. No desire to ever go back to commercial power.)
  3. K6LZX

    K6LZX Ham Member QRZ Page

  4. NO2A

    NO2A Ham Member QRZ Page

    This is exactly why I keep using my AL-80A!
  5. KC4EY

    KC4EY Ham Member QRZ Page

    Got my first amp at Christmas, after being a ham for 30 years
    I got the 572 and have enjoyed it. 572B tube maybecome more of an issue as time goes by only made one place in the world.
    Wish i had your antenna set up, only ground mounted BTV here.
    Still getting the hang of remembering the band switch. After logging the plate and load settings on tube amps, tuning is easy if you remember the band switch.
    Good luck.
    Report back on what you get and how you like it.
  6. AG6JU

    AG6JU Ham Member QRZ Page

  7. KD5RTY

    KD5RTY Ham Member QRZ Page

    I agree, the heathkits are great amps, easy to work on and a great piece of ham history. For a first and maybe only amp, I would still recomend something that covers all bands, as our interests, at least mine, change from time to time.
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